Re: peptide conjugation

Richard Laursen (laursen@bu.edu)
Wed, 20 Jan 1999 02:20:45 -0500

I don't know how you are trying to couple your peptide thiol to KLH (via a
disulfide, or some alkylating function?), but one approach you might
consider is to convert your peptide entirely to the disulfide and then
treat it with sulfite or thiosulfate to make a mono-S-sulfo derivative,
simultaneously releasing the thiol group of the second Cys residue. Then
couple this thiol to the KLH. If you are alkylating the thiol, you should
be able to do it in the presence of excess sulfite. This approach might
not work if you are coupling by making an intrapeptide disulfide, however.

Richard Laursen

>Hi everybody.
>We are trying to conjugate KLH to a peptide (via a free cysteine). The
>problem is that our peptide has two cysteine residues which form a
>disulphide bond quite readily. After reduction by DTT, the disulphide
>reforms during dialysis to remove the DTT from the reaction mixture. Apart
>from running a column or 'quicker' method of removing the DTT, so the
>disulphide doesn't have a chance to reform, does anybody have a suggestion
>as to how we might be able to maintain a free S-H to add the KLH to.
>Thanks in advance
>
>
>Michael Jobling
>Dept. of Pathology
>Uni. of Melbourne
>m.jobling@pathology.unimelb.edu.au

Richard A. Laursen
Department of Chemistry
Boston University
590 Commonwealth Ave.
Boston, MA 02215
Tel (617) 353-2491; FAX (617) 353-6466
email: <laursen@bu.edu>